The counting song “Eḥad mi yodei’a” (Who Knows One?), sung toward the very end of the seder, has been a standard element in Ashkenazi Haggadahs since at least the 16th century. It does not appear in most Sephardi versions of the Haggadah, but there are exceptions. In a few local traditions (like that of the Jews of Rhodes), it is generally sung in Ladino, with words somewhat different from the standard Hebrew text. Ty Alhadeff explains. (Audio recordings are included at the link below.)
[A]n exploration of . . . audio recordings of “Ken Supiense” [as the song is called in Ladino]—not only from Rhodes but also from other locales in the former Ottoman empire, including Salonica and present-day Turkey—reveals a wide variety . . . in the song’s wording and melody.
All versions of “Eḥad Mi Yodei’a,” whether in Hebrew or in Yiddish or Ladino translation, agree that, among the thirteen canonical references enumerated in the song, the number one always refer to one God and five always refers to the five books of the Torah. But there are some major variations among the Ladino versions. . . . Perhaps one of the most intriguing differences can be discerned in the varied references in the final, thirteenth, verse. The Rhodesli and Turkish versions do not refer to the thirteen attributes of God’s mercy as the original Hebrew text does, but rather to the renowned medieval sage Moses Maimonides’ thirteen principles of faith. . . .
The specific importance of these thirteen principles in the Sephardi tradition is reflected in the Ladino saying: está en sus treje (literally, “he is standing on his thirteen”), which refers to someone who is strong in his faith. According to [a] popular legend, . . . this expression dates back to the days of the Spanish Inquisition, when an inquisitor would ask of someone suspected of practicing Judaism in secret: “Está en su treje?” meaning: would a person abandon or stay steadfast in his belief in the thirteen principles of faith?